I do not recommend shooting standard 45ACP ammunition in these pistols as they were not built to withstand the pressures.

I have one of these and after testing it with a number of handloads, I am going to continue to use the lightest ones.

Whoever did the caliber conversion did it cheap and reamed the chamber mouths oversize.

I have no idea of the diameter of the barrel, but it must also be wide. I found .454 diameter bullets shot OK with a little leading. Smaller bullets gave more leading. I don’t have a mold that casts bullets .457, the larger dimensions are probably more appropriate.

I thought I would use some loads I developed in my 45 ACP revolvers. I had some Elmer Keith loads of a 250 with 6.5 grains Unique. That load was way to hot in a Webley. Actually stretched the top strap recess!

After that happened I realized that this mechanism is a lot weaker than any solid frame I have ever handled.

I also reconsidered using Elmer Keith loads in any of my 1917’s. His loads are entirely too hot for vintage pistols.

I eventually decided that 3.5 grains Bullseye was a good load. It shot to point of aim and was easy on the pistol.